An apparatus and method relating to handling a traffic message are described in the German patent application published under number DE 42 30 294 A1. The known apparatus is employed in a receiver for traffic messages according to the Radio Data System (RDS) Traffic Message Channel (TMC). According to RDS TMC, the traffic message is digitally coded and broadcast in parallel with the audio program. So when a traffic message is received, the audio program is also continued to be broadcast and the presentation of the audio is not be interrupted. The traffic message comprises in a coded way, an event indicating circumstances of importance to the traffic and a location to which the event relates. Examples of a traffic message are a traffic queue at a certain location on a highway and fog in a certain part of the country. After reception, the traffic message is decoded and presented to the user as an acoustic message and/or as a visible message is decoded and presented to the user as an acoustic message and/or as a visible message on a display.
The list of available location codes,is maintained by some standardization body in the relevant country, e.g. under the responsibility of the Ministry of Traffic of that country. A location code may indicate a single geographical position, a line between two positions and an area enclosed by a number of positions. Because the locations are coded, the location code of a traffic message can only relate to a location that has been defined in advance by the standardization body.
According to RDS TMC, a certain geographical region of interest, e.g. a country, is divided into a certain number of pre-defined areas. The known apparatus has the ability to filter the traffic messages and to present only those traffic messages that relate to a location in one or more of these areas. To this end, the user of the known apparatus indicates one or more areas for which traffic messages are to be presented. When an area has been indicated, all traffic messages with a location related to that area are presented to the user. If a user desires the presentation of traffic messages outside this area, he must indicate one or more further areas for which traffic messages are to be presented. A problem then occurs that all traffic messages of the original area and those of the further area or areas are presented and this may result in a relatively large number of traffic messages, of which a substantial part is not of interest to the user. This is the more true if the areas have a considerable size.
The invention relates to an apparatus for handling a traffic message. The apparatus comprises indication means for indicating a first area, a receiver for reception of the traffic message comprising an event and a location to which the traffic message relates, and a filter for determining whether the location is inside the first area and, if such is the case, passing on the traffic message for processing.
The invention further relates to an RDS TMC receiver comprising such an apparatus. The invention also relates to a navigation system comprising such an apparatus.
The invention further relates to a method of handling a traffic message. The method comprises an indication step indicating a first area, a reception step receiving the traffic message comprising an event and a location to which the traffic message relates, and a filtering step determining whether the location is inside the first area and, if such is the case, passing on the traffic message for processing.
It is an object of the invention to provide an apparatus of the kind set forth with an improved mechanism for filtering traffic messages. This object is achieved according to the invention in an apparatus that is characterized in that the apparatus further comprises expansion means for expanding the first area to a second area in at least one geographical direction by an expansion factor that is substantially smaller than the length of the first area in that geographical direction, and that the filter is arranged for determining whether the location is inside the second area and, if such is the case, passing on the traffic message for processing. The apparatus of the invention allows the definition of a new area of interest that is more according to the needs of the user. While in the known apparatus only complete pre-defined areas can be added to the first area, the new area according to the invention may be the first area to which a relatively small extension has been added. This is for instance advantageous where the user travels along the border of the first area and is interested in traffic messages from just across the border in the adjacent area, but does not want to be presented all traffic message from the adjacent area. Traffic messages from just across the border can be of interest for various reasons such as a traffic message with a weather report like the chance of fog or snow, since influence of these weather conditions will not precisely stop at the border; the user may be driving towards the adjacent area, but not yet interested in all traffic messages from that adjacent area; and the route followed may lead temporarily through the adjacent area.
The expansion of the first area into the second area results in the situation of partially overlapping areas. It is to be noted that this is different from the situation described in FIG. 5 of the patent document DE 42 30 294 A1, where the pre-defined areas overlap, simply because they have been defined that way. According to the invention, the area as defined beforehand is taken as input and expanded by the apparatus to fulfil the specific needs of the user. Also in the known situation of pre-defined overlapping areas, the apparatus of the invention may advantageously be used to expand such an area to an area that is more suitable to the user. Expanding the first area in all directions may be accomplished by enlarging an area with given co-ordinates by a certain factor. This apparatus also may be arranged to allow the user to specify the amount by which the first area is to be expanded. This gives the user the possibility to precisely define the second area, from which the traffic message are to be presented.
An RDS TMC receiver according to the invention is advantageously equipped with an apparatus according to the invention. The user of such a receiver is then able to precisely define the area from which traffic messages are to be presented.
A navigation system according to the invention is advantageously equipped with an apparatus according to the invention. The navigation system guides a driver along a route from an origin to a destination, based on information from a local road database. The received traffic message comprises information concerning the traffic conditions on the roads that is more actual than the information in the local database. The navigation system uses the information from the traffic message to inform the driver of events in relation to the route and/or may investigate whether an alternative route is better than the current one in view of the received actual information. Using the apparatus according to the invention, it is more precisely determined which traffic messages are to be processed by the navigation system. Reducing the number of traffic messages to be processed is advantageous since this reduces the computation effort involved.
It is a further object of the invention to provide a method of the kind set forth with an improved mechanism for filtering traffic messages. This object is achieved according to the invention in an apparatus that is characterized in that the method further comprises the step of expanding the first area to a second area in at least one geographical direction by an expansion factor that is substantially smaller than the length of the first area in that geographical direction, and that the filtering step includes determining whether the location is inside the second area and, if such is the case, passing on the traffic message for processing. By expanding the first area to the second area, an area of interest can be obtained that is more in line with the needs of the user. By using this second area as the basis for the filter, the traffic messages that are processed better match the actual need.
Further advantageous embodiments of the invention are described below and recited in the appended claims.